SLAB SET-DOWNS

There are a number of ways to create slab set-downs, depending on the nature of the set-down and structural design.

1. Separate Floor Slab

HOW TO:

• 1. Edit the floor slab by adding boundary lines around the setdown. This leaves a hole in the setdown area. DON'T cut a hole using Hole tool or shafts.

  2. Create another floor slab in the hole, set the top offset to match the setdown. If the overall slab structural thickness is to be maintained below the setdown use the same floor type, otherwise create a new thinner floor type.

  3. If the setdown has falls modify points of the setdown slab (see Graded Setdown below).

  4. Use the Join command to join the main and setdown slabs. They will display as one slab in sections.

WHEN TO USE:

• • Prefered method.

  • Setdown has vertical sides.

  • Soffit of setdown also has setdown (i.e. soffit is not flat).

  • You don't know whether the soffit has a setdown or not (assume it has to be safe).

  • Prefered method for structural analysis (keep your structural engineers happy).

2. Edited Floor Slab

HOW TO:

• 1. If the soffit is NOT going to follow the slope of the top: edit the floor slab type properties, edit Structure, tick the Variable tick box against the relevant layer in the Edit Assembly dialog box.

  2. Select the slab and use the Shape Editing commands in the menu bar to get the slope you require. Sometimes this is easier in a 3D view.

  3. Use the Join command to join the main and setdown slabs. They will display as one slab in sections.

WHEN TO USE:

• • Setdown edges slope (i.e. does not have vertical sides).

  • Soffit of setdown follows slope of top of slab.

  • Soffit of setdown will not be setdown (i.e. is always going to be flat).

3. Void Family

HOW TO:

• 1. Create (or use if already made) a Generic Model floor based family.

  2. Place reference planes with parameters: Width & Length as instance, thickness as type parameter.

  3. Create a void drawn at reference level and locked to reference planes.

  4. Place in project and stretch to fit setdown area. Set thickness parameter to match setdown depth.

You could also make it as an in-place family. This is not ideal but may be quicker if setdown is an unusual shape.

WHEN TO USE:

• • Quick and dirty - use when accuracy is not imortant.

  • Setdown is flat with no sloping.

  • Soffit below setdown is flat.

  • Sides of setdown are simple (separate families required for different shaped setdowns).

  • You are NOT going to export the model in formats other than Revit (some formats don't handle voids).